Accretion definition, an increase by natural growth or by gradual external addition; growth in size or extent. See more.
Alveoli are tiny sacs within our lungs that allow oxygen and carbon dioxide to move between the lungs and bloodstream. Learn more about how they function and quiz your knowledge at the end.
An alveolus is a tiny air sac formed at the tip of the lungs' smallest airways, the bronchioles. The primary function of the alveoli is the exchange of carbon dioxide for oxygen.Tissues within the alveoli also carry out secondary functions, such as the production of hormones, enzymes, and pulmonary surfactant.he exchange of carbon dioxide for oxygen is the primary function of the alveoli. The capillaries of the alveolus branch from both the pulmonary artery and the pulmonary vein.